It is quite true what Philosophy says that Life must be understood backwards. But that makes one forget the other saying that it must be lived --forwards. The more one ponders this, the more it comes to mean that life in the temporal existence never becomes quite intelligible, precisely because at no moment can I find complete quiet to take the backward-looking position.
It is the duty of the human understanding to understand that there are things which it cannot understand, and what those things are. Human understanding has vulgarly occupied itself with nothing but understanding, but if it would only take the trouble to understand itself at the same time it would simply have to posit the paradox.